The present invention relates to a serial printer having a carriage-moving pulse motor for reciprocating, in the main scanning direction, a head cartridge on which a printing head is mounted. More specifically, the invention relates to a serial printer having a function of monitoring whether the head carriage is correctly moving by a distance that is in accordance with the number of carriage drive pulses being applied to the carriage-moving pulse motor.
A conventional serial printer of the above type is disclosed in Japanese Patent Application Unexamined Publication No. Sho. 57-174291. In this serial printer, the number of pulses necessary for one scanning line reciprocation of the head carriage is stored in advance, and abnormality in the head carriage driving is detected by comparing the number of pulses actually sent to the carriage-moving motor with the stored number of pulses.
However, this method is deficient in that abnormality of the head carriage movement cannot be detected until the head carriage finishes its one reciprocation. The delay of the abnormality detection may cause serious damage to the carriage-moving pulse motor, recording sheet, etc.